The present invention relates to a server system having a network switching apparatus for moving an execution environment from one server to another, a plurality of servers connected to the network switching apparatus and a management server.
It has been desired to reduce TCO including a management cost of an IT system whose size has increased because of an increase in the number of apparatuses such as servers and networks for supporting an enterprise information system and consolidation of enterprise information systems to a data center due to advancement of outsourcing. It is necessary to improve flexibility of an IT system infrastructure in order to satisfy the requirements such as quick establishment of new services, support for load change, and shortening a service downtime during maintenance.
In order to satisfy the above-described requirements, simplification of management by utilizing server virtualization technologies has been paid attention. Server virtualization means virtualizing an execution environment of applications including OSes at a machine instruction level, and can configure a plurality of OSes on a physical server as an independent execution environment. By homogenizing virtual machine architectures to be presented to OSes, it becomes possible to normalize servers and expect a reduction of a management cost of servers more than managing physical servers of a plurality of vendors.
It is also possible to provide a flexible IT infrastructure by utilizing server virtualization technologies. A conventional IT infrastructure realizing some services has high dependency upon physical servers in terms of management. By weakening a couple to the IT infrastructure by utilizing server virtualization technologies, it becomes now easy to migrate one service running on a physical server to another physical server. These technologies are called server migration technologies.
A main server virtualization vender has recently developed live migration technologies for migrating one server to another without apparently stopping services (refer to “Live Migration of Virtual Machines”, by Christopher Clark, Keir Fraser, et. al., Symposium on Network Systems Design and Implementation, May, 2005). Support for load change, shortening a service downtime during maintenance and the like utilizing the live migration technologies have also been proposed.
It is necessary for server migration to inherit settings of a plurality of servers providing services, networks and storages. Since a plurality of apparatuses and a plurality of setting changes are associated with setting inheritance, a plurality of settings of a plurality of apparatuses are required to be changed with consistency. Since high reliability is required particularly for services supporting an enterprise information system, it is important to increase fault tolerance during settings and improve migration flexibility to expand migration adoption destinations.
Reference is made also to JP-A-2007-286709.
In order to reliably perform settings of each apparatus regarding server migration, it is generally desired that an issue of a setting operation for each apparatus ends either as a normal termination after completion of requested settings or as an abnormal termination in a state before settings if a fault occurs and requested settings cannot be executed. This nature is called atomicity of setting operation.
However, in migration involving a plurality of apparatuses, the state before settings may not be recovered easily in some cases depending upon the fault state.
Namely, for server migration, even one apparatus requires a plurality of settings for a migration source server and a migration destination server. Particularly for a network switch interconnecting both the servers, a plurality of settings are essential. In this case, it is necessary to issue setting commands for a plurality of setting items, confirm whether execution of each command has succeeded or failed, and to describe a script to be executed when the command execution was failed. There arise therefore the following problems. Statements of a network setting script in a server migration process becomes complicated. Further, since the number of threads which perform settings of the network switch is not necessarily a single, it is necessary to execute exclusive control that while one thread performs plurality of settings, setting for the same item by another thread should be inhibited. The setting process becomes further complicated because of this exclusive control. Because the server migration process flow becomes complicated, management itself becomes also complicated. Further, it becomes difficult to add a new function of the migration script to deal with a new fault and to perform maintenance of the migration script each time the function is added.
Conventional server migration is realized on the assumption that settings for networks and storages are performed in advance, and lacks setting flexibility. There arise therefore the following problems. For example, the configuration and settings cannot be changed depending upon the status of a physical server for hosting a migration destination virtual server. Further, in an environment where a migration destination is dynamically selected by server virtualization technologies, it is not possible to configure a virtual server and perform settings of networks, storages and the like in advance. Particularly in a case where even a migration destination server cannot be configured, it is not possible even to judge resources necessary for settings from the current configuration.
Further, conventional live migration technologies are realized on the assumption that storages are shared by SAN and do not deal with migration in an environment where there are systems and data volumes in a hard disc built-in a server. On the other hand, there is a server migration method utilizing deploy technologies for execution environment distribution. However, the deploy technologies are not technologies suitable for server migration and server identification is performed based on network physical addresses. There arise therefore the following problems. If the deploy technologies are directly applied to server migration, network physical addresses will be changed. Further, since network setting is associated with not only network switches but also settings of a network interface on the server side, there arise some inconveniences if the physical addresses are changed.